Hybrid power converter with two-phase control of flying capacitor balancing

Abstract

A power converter for converting an input voltage at an input of the power converter into an output voltage at an output of the power converter may include a first power converter branch comprising a first capacitor, a first switch network, and a first inductor, the first switch network arranged to selectably couple the first capacitor between an input voltage, a first reference voltage, and a first terminal of the first inductor, wherein a second terminal of the first inductor is coupled to an output node; a second power converter branch comprising a second capacitor, a second switch network, and a second inductor, the second switch network arranged to selectably couple the second capacitor between the input voltage, a second reference voltage, and a first terminal of the second inductor, wherein a second terminal of the second inductor is coupled to the output node; and a third switch network between the first power converter branch and the second power converter branch, wherein the third switch network is arranged to selectably couple the first and second capacitors in series or in parallel, to allow enable charge balancing between the first capacitor and second capacitor.

What is claimed is: 
     
       1. A power converter for converting an input voltage at an input of the power converter into an output voltage at an output of the power converter, the power converter comprising:
 a plurality of phases including at least a first phase and a second phase, each of the plurality of phases comprising a plurality of switches and a flying capacitor comprising a first capacitor terminal and a second capacitor terminal; and 
 balancing switches comprising:
 a first switch coupled between the second capacitor terminal of the first phase and the first capacitor terminal of the second phase; 
 a second switch coupled between the first capacitor terminal of the second phase and the first capacitor terminal of the second phase; 
 a third switch coupled between the first capacitor terminal of the first phase and the first capacitor terminal of the second phase; and 
 a fourth switch coupled between the second capacitor terminal of the first phase and the second capacitor terminal of the second phase. 
 
 
     
     
       2. The power converter of  claim 1 , further comprising a control circuit configured to operate the power converter in a forward 3-level buck mode having a plurality of switching states, wherein:
 for at least a first one of the plurality of switching states, the first switch is activated to couple the flying capacitor of the first phase and the flying capacitor of the second phase in series; 
 for at least a second one of the plurality of switching states, the second switch is activated to couple the flying capacitor of the first phase and the flying capacitor of the second phase in series; and 
 for at least a third one of the plurality of switching states, one of the third switch and the fourth switch is activated to couple the flying capacitor of the first phase and the flying capacitor of the second phase in parallel. 
 
     
     
       3. The power converter of  claim 1 , further comprising a fifth switch coupled between the output and the first capacitor terminal of the second phase. 
     
     
       4. The power converter of  claim 3 , further comprising a control circuit configured to operate the power converter in a bypass mode wherein the fifth switch is activated. 
     
     
       5. A method for converting an input voltage at an input of the power converter into an output voltage at an output of the power converter, wherein:
 the power converter comprises:
 a plurality of phases including at least a first phase and a second phase, each of the plurality of phases comprising a plurality of switches and a flying capacitor comprising a first capacitor terminal and a second capacitor terminal; and 
 balancing switches comprising:
 a first switch coupled between the second capacitor terminal of the first phase and the first capacitor terminal of the second phase; 
 a second switch coupled between the first capacitor terminal of the second phase and the first capacitor terminal of the second phase; 
 a third switch coupled between the first capacitor terminal of the first phase and the first capacitor terminal of the second phase; and 
 a fourth switch coupled between the second capacitor terminal of the first phase and the second capacitor terminal of the second phase; and 
 
 
 the method comprises operating the power converter in a forward 3-level buck mode having a plurality of switching states, wherein:
 for at least a first one of the plurality of switching states, the first switch is activated to couple the flying capacitor of the first phase and the flying capacitor of the second phase in series; 
 for at least a second one of the plurality of switching states, the second switch is activated to couple the flying capacitor of the first phase and the flying capacitor of the second phase in series; and 
 for at least a third one of the plurality of switching states, one of the third switch and the fourth switch is activated to couple the flying capacitor of the first phase and the flying capacitor of the second phase in parallel. 
 
 
     
     
       6. The method of  claim 5 , wherein the power converter further comprises a fifth switch coupled between the output and the first capacitor terminal of the second phase. 
     
     
       7. The method of  claim 6 , further comprising operating the power converter in a bypass mode wherein the fifth switch is activated. 
     
     
       8. An integrated circuit for use in a power converter for converting an input voltage at an input of the integrated circuit into an output voltage at an output of the power converter, the integrated circuit comprising:
 a plurality of phases including at least a first phase and a second phase, each of the plurality of phases comprising a plurality of switches and a flying capacitor comprising a first capacitor terminal and a second capacitor terminal; and 
 balancing switches comprising:
 a first switch coupled between the second capacitor terminal of the first phase and the first capacitor terminal of the second phase; 
 a second switch coupled between the first capacitor terminal of the second phase and the first capacitor terminal of the second phase; 
 a third switch coupled between the first capacitor terminal of the first phase and the first capacitor terminal of the second phase; and 
 a fourth switch coupled between the second capacitor terminal of the first phase and the second capacitor terminal of the second phase. 
 
 
     
     
       9. The integrated circuit of  claim 8 , further comprising a control circuit configured to operate the power converter in a forward 3-level buck mode having a plurality of switching states, wherein:
 for at least a first one of the plurality of switching states, the first switch is activated to couple the flying capacitor of the first phase and the flying capacitor of the second phase in series; 
 for at least a second one of the plurality of switching states, the second switch is activated to couple the flying capacitor of the first phase and the flying capacitor of the second phase in series; and 
 for at least a third one of the plurality of switching states, one of the third switch and the fourth switch is activated to couple the flying capacitor of the first phase and the flying capacitor of the second phase in parallel. 
 
     
     
       10. The integrated circuit of  claim 8 , further comprising a fifth switch coupled between the output and the first capacitor terminal of the second phase. 
     
     
       11. The integrated circuit of  claim 10 , further comprising a control circuit configured to operate the power converter in a bypass mode wherein the fifth switch is activated.